Uranium Found in Kansas Drinking Water Supplies

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LAWRENCE, Kansas, November 28, 2008 (ENS) - The radioactive element uranium has been found above federal limits in the drinking water supplies of nine Kansas communities, says Don Whittemore, a geochemist with the Kansas Geological Survey. Now these communities must devise solutions to bring down the uranium levels.

Possible solutions include relocating wells, buying water from other suppliers, or installing a treatment system, such as reverse osmosis.

In 2003 the U.S. Environmental Protection Agency set a drinking water standard for uranium at a maximum contamination level of 30 parts per billion and gave public water providers until December 2007 to complete monitoring. Not all Kansas communities were able to meet the standard.

"The Arkansas River corridor in southwestern Kansas is especially susceptible to levels of uranium above EPA standards due to water-consuming agricultural practices in eastern Colorado," said Whittemore.

"Low levels of naturally occurring uranium picked up by the river from Cretaceous shales in Colorado are increased as water is lost to evaporation and transpiration," he explained.

Water from the river and shallow aquifers in Colorado is diverted into irrigation canals, farm fields, and reservoirs, giving it greater exposure to evaporation and transpiration. As a result, flows decline and concentrations of almost all chemical constituents, including uranium, increase before the river enters Kansas.

"When these enriched levels are added to natural uranium already present in groundwater in portions of the Ogallala aquifer in Kansas, it doesn't take much to get above the standard," Whittemore said.

The High Plains aquifer, which includes the Ogallala, is the source of most drinking water in western Kansas.

Some cities along the Arkansas River, including Garden City and Dodge City, have approaches in place to reduce contaminants and they were able to meet EPA standards.

But nine Kansas communities and water districts must now deal with water supplies that consistently registered above federal standards. They are - Atwood, Clay Center, Gaylord, Morganville, Norton, Oberlin, Lakin, Rooks County Rural Water District 1, and a Garden City subdivision. Private wells are not monitored.

In Lakin, population 2,115 on the historic Santa Fe Trail, uranium levels in the city's main well were above the standard over the four-year monitoring period.

"When out of compliance, communities such as Lakin are responsible for fixing the problem," Whittemore said.

A water supply that does not meet EPA standards has to be monitored quarterly while the community works to reduce the contaminants. Lakin and the other Kansas communities are currently investigating their options.

Because long-term exposure to high levels of uranium may cause kidney damage and increase the risk of cancer, the maximum contamination level for uranium is a primary standard, meaning it was enacted to protect public health and is legally enforceable. Natural uranium's capacity to be toxic, or poisonous, not its weak radioactivity, is what raises health concerns.

"Like mercury and arsenic, uranium can be toxic in high doses over a long period," Whittemore said.

As in the Arkansas River valley, high levels of uranium in other parts of the state are derived from Cretaceous-age shales deposited between 65 and 142 million years ago. The uranium leaches into the groundwater when the subsurface shales are weathered by rainfall recharge.

"Cretaceous shales tend to contain higher concentrations of naturally occurring uranium than other rocks in the Great Plains," Whittemore said.

The Kansas Department of Health and Environment's Bureau of Water is responsible for regulating all public water supply systems and has adopted the EPA's drinking water standards.

{Photo: The water tower in Norton, Kansas, one of nine communities where uranium above federal standards has been found in drinking water (Photo by John Nicolas)}